FIG. 1 of the accompany drawings shows an image sensor constructed in accordance with the prior art. The image sensor comprises a frame 12, a light source unit 17 mounted in the frame 12, a gradient index lens array 15 mounted in the frame 12 and commercially available under the trade name "SELFOC lens array", a light receiving unit 18 mounted in the frame horizontally at the inner bottom thereof, an external connector 19 extending outwardly from the frame 12 at one side, and a glass sheet 13 mounted on the frame 12 at the top.
The light source unit 17 comprises a base plate 17a and a light emitting diode (LED) 17b having a lens and mounted on the base plate 17a. The light source unit 17 is disposed inclined 45 degrees relative to a plane perpendicular to the longitudinal axis of the frame 12.
The light receiving unit 18 comprises a base plate 18a and a photosensor (e.g. photodiode array) 18b, in which an array of light receiving parts are disposed on the base plate 18a and extend in a direction perpendicular to the plane of FIG. 1.
The gradient index lens array 15 is supported within the frame 12 above the photosensor 18b.
The base plates 17a and 18a are electrically connected with the internal terminal of the connector 19 through leads (not shown).
Light emitted from the light source unit 17 irradiates an original document 20 with an angle of 45 degrees through the glass sheet 13 and is reflected by the document 20 toward the gradient index lens array 15. After passing through the gradient index lens array 15, the light is condensed onto the photosensor 18b wherein the light is converted into an electrical signal.
The image sensor of the prior art requires the light source 17 and light receiving units, 18 which are separately constructed and also the leads connecting these units 17, 18 with the connector 19. This makes it difficult to reduce the number of assembling steps and to decrease the manufacturing cost. Having these separate units prevents the entire size of the image sensor from being reduced.